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Thursday, December 8, 2016

Thursday Snow Nowcast at 3 PM: Snow Moving in Faster Than Expected

Well, our models may have had the right idea of the threat of snow, but the recent runs clearly have a serious timing error. The snow will arrive 4-5 hours earlier than expected.

The latest radar image (2:27 PM) shows the story--the precipitation shield from the warm front has reached the south Sound. Once precipitation starts aloft, it takes about an hour to reach the surface (need to humidify the layer below)

The latest visible satellite image shows an impressive cloud band with the warm front.

Let me show you some traffic cams.

It has been snowing in Portland for hours.

Vancouver

Longview

Here is the Chehalis Airport

Centralia.

Dupont, north of Olympia at 3:30

It should starting snowing at the surface in Olympia by 3PM. At the current rate of progress, the snow will get to Tacoma around 4 PM and Seattle by 5-5:30 PM.

There appears to be multiple bands...the first band is producing the above snow. It appears to be weakening over southern Puget Sound...and slowed down. So it looks like Seattle commute will be ok. The second band, which should arrive later (if the models are right), well be more of a threat for Seattle and points north...later in the evening.

Cliff,Baased on the models yes but ,mostly on your on-going analysis of them, I predict the first snowflake at my house to occur in exactly 16 minutes and 30 seconds based on the radar info and your meteorological information regarding precipitation calculated for our elevation and windspeed history over the last 45 minutes. I will go out on a limb and predict 2.3" of total snow accumulatiom by 4:20 am tomorrow. I will Et you know how it turned out. Thanks professor.

Snow at SeaTac Airport from the first band that didn't dissipate from about 19:26 to 19:50. Anticipating the next band of precipitation. Hopefully to start at 20:10ish?Surfaces on runways have been reporting at below freezing.

The "first band" never panned out here in Mukilteo. I saw about 3 flakes at 6 p.m. but that was it. Light snow began at 9-9:30, so the forecast was spot on for us. Still snowing but I don't expect we'll see more than a dusting.

No snow at 11pm in north Whatcom County; just our standard non-stop northeaster. Thursday temps in Bellingham were several degrees higher than farther north, and wind wasn't nearly as significant. Generally we don't get snow until/unless this wind dies down. Then there's a a light snowfall, after which the wind picks back up and wreaks havoc.

Haven't looked at the GFS yet.my son is hogging our computer to finish quarter final reports..what is it showing? Most forecasts for next week show super cold again but dry...when there is moisture it says rain....

Always dependent on exact geography, but from my point of view (north seattle), i'd say Professor Mass's snowmeggeon-2016 forecast was spot on. Came late, about an inch, melting away in the morning, ("just like she..." shaddup!) Well done!

❄️❄️❄️Do you love to play in the snow but don't want to drive all the way to the Pass for fun? I shouldnt do this and let the secret out but fot Cliff Mass fans here it is. 30 minutes from Seattle is a wonderful State Park at Rattlesnake Lake. Exit off I-90 and go up the hill on Cedar Falls Way and at the end of the road is a beautiful park with about 6 inches on the ground right now, and they plow the road and parking lot. Have fun out there.

I am a happy camper this morning. We have snow on the ground, and at about 500 feet elevation, just above Lake Goodwin, Northwest of Marysville, it is snowing. It may not all be snow, temp is 33, but it's snowing.

It's still snowing in Glacier - over 2" powder has accumulated since last night. It's warming right now; flakes are getting bigger and we may be heading back to 32/transition point. There are a lot of Weather Underground personal weather stations that report continuously via internet now. "Glacier West Central" is: https://www.wunderground.com/personal-weather-station/dashboard?ID=KWADEMIN7#history

I wonder if the U-crew makes use of the data. A number of us calibrate and cross-check.

Stopped snowing here in Bellingham at about 4:30 PM; looks like clouds are thinning. However, there is still a breeze from the northeast. It seems that the Frazer outflow is still here in Bellingham. Snow in my yard (E. Victor and Guide Meridian across from Cornwall Park) is try (not wet/sticky), which makes me guess that temps here in Bellingham have yet to make it above freezing.

Yep, as Troy said, on Friday evening decent snowfall is still decent here in north Whatcom County. Supposed to warm up a few degrees overnight & tomorrow, and the slush/freezing rain mix could be "interesting".

Joanna, when I said Friday's event didn't amount to much, I meant in relative terms. : ) We did get a couple of inches in my part of the county, too, but as is so often the case, snow here is accompanied by the northeaster & it doesn't settle evenly. Mostly just windy snow throughout the day, nothing noteworthy. More accumulations tonight, like Troy said, and we'll see how it plays out with wind + temps!

1:15 AM, Mon. 10 miles SE of Chehalis. 600' elev. It's SNOWING. Most of the snow from last week finally disappeared today. Loks like we're heading into a cold snap. A long one. Wonder how long it will hang on? Lew